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Overview
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Encephalitis
Contents
Overview
Symptoms
Causes
Diagnosis
Treatment
Complications
Encephalitis is an uncommon but serious condition in which the brain becomes inflamed (swollen).
It can be life threatening and requires urgent treatment in hospital.
Anyone can be affected, but the very young and very old are most at risk.
Symptoms of encephalitis
Encephalitis sometimes starts off with flu-like symptoms, such as a high temperature and headache.
More serious symptoms come on over hours, days or weeks, including:
confusion or disorientation
seizures or fits
changes in personality and behaviour
difficulty speaking
weakness or loss of movement in some parts of the body
loss of consciousness
Dial 999 for an ambulance immediately if you or someone else has these more serious symptoms.
Causes of encephalitis
It's not always clear what causes encephalitis, but it can be caused by:
viral infections – very rarely, encephalitis may be caused by the common viruses that causes cold sores (herpes simplex) or chickenpox (herpes varicella) spreading to the brain
a problem with the immune system, the body's defence against infection – sometimes something goes wrong with the immune system and it mistakenly attacks the brain, causing it to become inflamed
bacterial or fungal infections – these are much rarer causes of encephalitis than viral infections
Some types of encephalitis are spread by mosquitoes (such as Japanese encephalitis), ticks (such as tick-borne encephalitis) and mammals (such as rabies).
You cannot catch encephalitis from someone else.
Treatments for encephalitis
Encephalitis needs to be treated in a hospital. The earlier treatment is started, the more successful it's likely to be.
Treatment depends on the underlying cause, but may include:
antiviral medicines
steroid injections
treatments to help control the immune system
antibiotics or antifungal medicines
painkillers to reduce discomfort or a high temperature
medicine to control seizures or fits
support with breathing, such as oxygen through a face mask or a breathing machine (ventilator)
How long someone with encephalitis needs to stay in hospital can range from a few days to several weeks or even months.
Recovering from encephalitis
Some people eventually make a full recovery from encephalitis, although this can be a long and frustrating process.
Many people never make a full recovery and are left with long-term problems caused by damage to their brain.
Common complications include:
memory loss
frequent seizures or fits
personality and behavioural changes
problems with attention, concentration, planning and problem solving
persistent tiredness
These problems can have a significant impact on the life of the affected person, as well as their family and friends.
But help and support is available.
Preventing encephalitis
It's not always possible to prevent encephalitis, but some of the infections that cause it can be prevented with vaccinations.
These include the:
measles, mumps and rubella (MMR) vaccine – a routine vaccination offered to all children in England
Japanese encephalitis vaccine – recommended for travellers to at-risk areas, such as parts of Asia
tick-borne encephalitis vaccine – recommended for travellers to certain parts of Europe (but not the UK) and Asia
rabies vaccination – recommended for travellers to at-risk areas where access to medical care is likely to be limited
Speak to a GP surgery if you're not sure whether your vaccinations are up to date, or you're planning to travel abroad and do not know if you need any vaccinations.
Page last reviewed: 03 December 2019
Next review due: 03 December 2022
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